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Thursday, August 31, 2017

Genovation Parallel Micropad 621

I bought several of these on eBay. I got 3 of the Parallel 621 keypads and 1 of the Serial 623. They were a deal for $6 each. They are very old, the drivers available for them are for DOS and Windows 3.1.

It is a modular design and the controller board is easily removed. The matrix has an easy to access pin header. The matrix has diodes for full anti-ghosting.

They are in pretty good condition considering their age.

The switches are some generic clicky ALPS. The keycaps are doubleshot ABS.

The shell is held together with 4 screws hidden under the adhesive rubber feet.

The PCB assembly is held in place by another 4 screws.

The controller board is held on with double stick tape.

The 9 pin header is the 4 column x 5 row matrix connector.

From top to bottom the pins are:

Col 4

Col 3

Col 2

Col 1

Row 5

Row 4

Row 3

Row 2

Row 1

The diodes are oriented Row to Col.

I connected it to a Pro Micro with pre-made jumper wires.

D2

D1

D0

D4

C6

D7

E6

B4

B5

I taped the connectors together to keep them in order.

I soldered pin headers to Pro Micro. It is held down with 3M VHD heavy duty double stick foam tape.

The matrix is so simple I used kbfirmware.com to create the firmware hex. The JSON file I used is here.

Domo Pad

Two PCB's are used, one as a base. The PCB is under 100mm x 100mm, you can order 10 for $2 from Easyeda.com. DHL shipping is another $18, airmail is cheaper but can take over a month. You can have only one $2 special per order. Additional 100mm x 100mm PCBs are also discounted to $5 for 10, which is still very cheap.

It shares the same matrix pinout as the Let's Split Rev 2 and will run
the same firmware. The primary difference (other than switch spacing) is
the lack of jumpers. The Half IOTA is setup for Serial communication
between the halves. I2C jumpers and pull up resistors are not present.
The jumpers for the TRRS jacks are not necessary since the jacks used
are surface mount and are wired correctly for each side.

The boards are designed to be assembled using a second PCB as the base.
There is no switch plate, PCB mount switches must be used.

M2 spacers and screws. You must install the spacers in the top
plate before installing the switches since the screw holes are not
accessible with the switches in place.

All of the unused pins are broken out to pads at the top of the boards.
The unused connection in the TRRS connector is also broken out to a
pad.

The Pro Micro's are in sockets. They must be oriented correctly for each half to work.

The TRRS jack is from Sparkfun. Part PRT-12639, they are $0.95 each. Sparkfun has distributors in many countries.

LCSC has a comparable part PJ-320D-A. The registration pins are much smaller so it needs to be held in place when soldering to keep them straight. They are only $0.0633 each, with a 5 piece minimum.

Monday, August 28, 2017

Gherkin with a 4 key outrigger

The plate cutouts are an experiment. I wanted a single PCB that could be used as the top and bottom plates. The cutouts have notches where a small flush cutter can snip the thin supports. The bottom plate is left intact.

The Gherkin PCB could be installed in either orientation. The LEDs on the Gherkin could be used too but the LEDs on the 4 Key macropad could not. "Ground" on the 4 Key macropad is used as the column in the extended Gherkin matrix.

The Gherkin's matrix is extended by one column. That column is connected to F6. The 4 switches are connected to rows 0-3 through diodes. This retains full anti-ghosting, NKRO.

Full NKRO. NKRO is toggled on/off by holding down Q and N while plugging in the USB connector. This is saved in EEPROM and only needs to be done once.

The modified Gherkin firmware is on github. It has a very basic layout by default with no layers. The plate file is here.

Thursday, August 24, 2017

Gherkin PCB without silkscreen

I wanted some plain white PCB's. I ordered them without the GTO and GBO gerber layers. The GTO is the top silkscreen layer, GBO is the bottom silkscreen layer. You have to remove these files from the zip file before uploading them to EasyEDA. Other EDA programs may use different file extensions than these, so preview whatever you upload to be sure it is correct.

Without the silkscreen layers you lose all the parts legends. You will need some other way of identifying correct part placement and orientation.

Tuesday, August 22, 2017

These PCBs are the same outer dimensions as the keyboard PCBs. Holes for each of the switches and the Pro Micro were cut out. This is probably more elaborate than needed. I could have just cut out larger rectangles between each screw hole. It is very sturdy when assembled.

I chose 1.0mm PCB so that I could match it with the correct spacer lengths which are all multiples of 1mm. I used 4mm M2 spacers which fit snugly in the middle pieces. Some were too tight and I had to sand them down slightly to fit.

No gaps for things to get into the keyboard. The main problem I have with sandwich style keyboard cases is the gap where things can make contact with the electrical contacts inside. You can see this gap in this post.

Wednesday, August 16, 2017

Ed's smallest keyboard. 16mm spacing using the 16mm 30% PCB. A custom top plate was made to look like the rack mount keyboard Ed uses. The plates were sanded down and dyed with iDye Poly Silver Grey dye.

Tuesday, August 1, 2017

Gherkin Alps switch compatible with RGB underglow

Second version of the Alps compatible Gherkin PCB. Main change is the rotation of the switches so the switch pins are all towards the middle of the board. This leaves a large flat area along the edges where a WS2812b LED strip can be placed. Power and data pads on the corners to solder the LED strip to.

The green solder mask on the top and bottom plates were sanded down to the bare fiberglass material which is translucent.

20 WS2812b LEDs are probably too many. This is the 60 per meter type, the 30 per meter type would be a better fit.

Side view. 9mm spacers with a low profile socket for the Pro Micro.

The LED strips are connected with solder bridges to the long pads.

Closeup of the solder bridges. A piece of kapton tape was placed across the pads to prevent the solder from flowing along the entire length of the long solder pads. Don't try this with regular tape, it will melt and you will have a sticky mess.